The user agent is a compatibility label your browser sends with every request — messy because decades of history are baked into it.
Short answer
Every UA claims Mozilla-compatibility for legacy reasons In practice, open the linked tool below and compare your live values with the explanations that follow.
How it works
What Is a User Agent? comes down to reading documented browser signals and interpreting them honestly — including when the browser withholds them.
- Every UA claims Mozilla-compatibility for legacy reasons
- OS, engine and browser tokens follow in order
- Reduction now freezes many details
At a glance
| Signal | What you learn |
|---|---|
| Browser report | Live values for this device right now |
| Withheld fields | Privacy protections, not hardware faults |
| Best next step | Use the related tool to verify your own setup |
Practical steps
- Open the related tool and note the highlighted rows.
- Compare them with the points above.
- If something looks off, check zoom, extensions and private mode, then retest.
Try it live: open the related checker and see your own values.
FAQ
Why is the string so weird?
Each generation imitated the last to avoid being blocked. The clutter is fossilized compatibility, not encryption.
Related reading
Bottom line: Reduction now freezes many details When in doubt, trust the live tool over memory — browsers change, and support varies by browser.